Length-adjustable film applicator

ABSTRACT

A film applicator includes an outer tube, an inner tube in the outer tube, and an adjustment assembly in the inner tube. The adjustment assembly has a threaded shaft fixed in the inner tube, a retaining nut mounted around the threaded shaft, a turning knob rotatably mounted around the threaded shaft, and an adjustment ring threadedly provided around the threaded shaft. When at a first position, the adjustment ring pushes the turning knob against the retaining nut and allowing the threaded shaft to rotate the inner tube with respect to the outer tube, thereby adjusting the exposed length of and securing the inner tube. When at a second position, the adjustment ring does not push the turning knob, which therefore cannot drive the inner tube into rotation. The inner tube thus stays at the secured position.

BACKGROUND OF THE INVENTION 1. Technical Field

The present invention relates to a film applicator and more particularly to a film applicator whose length is adjustable.

2. Description of Related Art

A film applicator is typically used to enhance the efficiency of packaging with film. To operate a film applicator, a roll of film is mounted around the rotating shaft of the applicator, and the film is pulled off the roll by holding the handle of the applicator with both hands. The rotating shaft allows the film to be wrapped around a product rapidly.

In the prior art, the length of the rotating shaft cannot be adjusted, and yet each roll of film may have a different width for use with a particular product. As a result, rotating shafts of various lengths must be kept at hand in order to work with films of different widths respectively, which is inconvenient. In addition, replacing the rotating shaft is no easy task because the shaft must be dismounted in its entirety.

BRIEF SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a film applicator whose length can be adjusted according to the width of the film to be used, thus not only reducing cost but also enhancing ease of operation.

To achieve the objective, the film applicator of the present invention includes a stand, an inner tube assembly, and an adjustment assembly. The stand has a supporting base and an outer tube. The outer tube has one end provided at the supporting base. The inner tube assembly has an inner tube, a positioning column, and a positioning sleeve. The inner tube is provided in the outer tube of the stand in a rotatable and axially displaceable manner. In addition, the inner tube has an operation end outside the outer tube and a positioning end in the outer tube. The positioning column is provided at the positioning end of the inner tube and can move with the inner tube. The positioning sleeve is threadedly connected to the positioning column such that, by rotating the inner tube, the positioning column is driven to either press the positioning sleeve tightly against the outer tube of the stand or loosen the positioning sleeve from the outer tube of the stand. When the positioning sleeve is pressed tightly against the outer tube of the stand, the inner tube is secured in position and cannot move axially. When the positioning sleeve is loosened from the outer tube of the stand, however, the inner tube can move axially with respect to the outer tube so that the exposed length of the inner tube (herein defined as the length of the portion of the inner tube that is exposed from the outer tube) can be adjusted. The adjustment assembly has a threaded shaft, a retaining nut, a turning knob, and an adjustment ring. The threaded shaft has one end fixed at the operation end of the inner tube and the opposite end threadedly connected with the retaining nut. The threaded shaft further has a flange. The turning knob has a collar, which lies between the retaining nut and the flange of the threaded shaft and through which the turning knob is rotatably mounted around the threaded shaft. The adjustment ring is threadedly provided around the threaded shaft and between the operation end of the inner tube and the turning knob and can be displaced axially along the threaded shaft between a first position and a second position.

When the adjustment ring is at the first position, the collar of the turning knob is pushed against the retaining nut by the adjustment ring. In consequence, the turning knob and the threaded shaft form a single unit, and the inner tube can be rotated with respect to the outer tube via the threaded shaft in order to have its exposed length adjusted and position secured. When the adjustment ring is at the second position, it is away from the collar of the turning knob and therefore allows the turning knob to rotate freely without driving the inner tube into rotation, and the inner tube is thus kept at the secured position.

The structure, features, and methods of assembly and use of the film applicator of the present invention will be described in more detail below with reference to an illustrative embodiment. However, as a person of ordinary skill in the art would understand, the detailed description and the specific embodiment provided herein serve only to shed light on, but not to restrict the scope of, the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view showing the film applicator according to an embodiment of the present invention used in conjunction with a roll of film:

FIG. 2 is a perspective view of the film applicator in FIG. 1:

FIG. 3 is an exploded perspective view of the film applicator in FIG. 1:

FIG. 4 is a sectional view of the film applicator in FIG. 1, showing in particular the inner tube before length adjustment:

FIG. 5 is a partial enlarged view of FIG. 3, showing in particular how the conical portion of the positioning column abuts against the wall of the conical groove of the positioning sleeve;

FIG. 6 is another partial enlarged view of FIG. 3, showing in particular the structure of the adjustment assembly;

FIG. 7 is similar to FIG. 4, showing in particular the adjustment ring at the second position and the conical portion of the positioning column away from the wall of the conical groove of the positioning sleeve;

FIG. 8 is similar to FIG. 7, showing in particular the inner tube after length adjustment; and

FIG. 9 is similar to FIG. 8, showing in particular the adjustment ring at the second position.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 to FIG. 3, the film applicator 10 according to an embodiment of the present invention includes a stand 20, an inner tube assembly 30, and an adjustment assembly 40.

The stand 20 has a supporting base 22, an outer tube 24, and a handle 26. The supporting base 22 is configured to support the bottom end of a roll of film 12. The outer tube 24 has one end fixed at the top side of the supporting base 22 and is so configured that the roll of film 12 can be mounted around the outer tube 24. The handle 26 has one end fixed at a peripheral portion of the supporting base 22 and is configured to be held with both hands.

As shown in FIG. 3 to FIG. 5, the inner tube assembly 30 has an inner tube 31, a positioning column 32, and a positioning sleeve 33. The inner tube 31 is provided in the outer tube 24 of the stand 20 in a rotatable and axially displaceable manner and is so configured that the roll of film 12 can be mounted around the inner tube 31, too. The inner tube 31 has an operation end 312 outside the outer tube 24 and a positioning end 314 in the outer tube 24. The positioning column 32 has a joining portion 322, a conical portion 324, and a threaded connection portion 326. The positioning column 32 is fixedly connected to the positioning end 314 of the inner tube 31 via the joining portion 322 in order to move along with the inner tube 31. The conical portion 324 of the positioning column 32 is connected to one end of the joining portion 322, and the outer diameter of the conical portion 324 is reduced in a direction away from the joining portion 322. The threaded connection portion 326 of the positioning column 32 extends from the pointed end of the conical portion 324 and has a retaining ring groove 328. The positioning sleeve 33 has two opposing sleeve halves 34, which are mounted around the positioning column 32 via a restriction ring 35 and each have a pressed portion 36. The inner peripheries of the pressed portions 36 of the sleeve halves 34 jointly form the wall of a conical groove 37, and the wall of the conical groove 37 abuts against the conical portion 324 of the positioning column 32. The outer peripheries of the pressed portions 36 of the sleeve halves 34 abut against the inner periphery of the outer tube 24. The positioning sleeve 33 further has a nut 38 provided between the sleeve halves 34 and threadedly connected to the threaded connection portion 326 of the positioning column 32.

While the inner tube 31 is rotated, the conical portion 324 of the positioning column 32, whose threaded connection portion 326 is threadedly connected with the nut 38 of the positioning sleeve 33, either pushes or is moved away from the wall of the conical groove 37 of the positioning sleeve 33. When the conical portion 324 of the positioning column 32 pushes the wall of the conical groove 37 of the positioning sleeve 33, the two pressed portions 36 of the positioning sleeve 33 are driven outward and therefore pressed tightly against the outer tube 24 to keep the inner tube 31 from moving with respect to the outer tube 24. When the conical portion 324 of the positioning column 32 is away from the wall of the conical groove 37 of the positioning sleeve 33, the two pressed portions 36 of the positioning sleeve 33 do not apply any pushing force to the outer tube 24, so the inner tube 31 can move with respect to the outer tube 24. To prevent the threaded connection portion 326 of the positioning column 32 from separating from the nut 38 of the positioning sleeve 33, a retaining ring 39 is provided in the retaining ring groove 328 of the threaded connection portion 326 of the positioning column 32 to serve as a stopper.

As shown in FIG. 3, FIG. 4, and FIG. 6, the adjustment assembly 40 has a threaded shaft 41, a turning knob 42, and an adjustment ring 43. A first retaining nut 44 and a second retaining nut 45 are respectively and threadedly fixed at the top end and the bottom end of the threaded shaft 41, wherein the second retaining nut 45 is embedded in the operation end 312 of the inner tube 31 to secure the threaded shaft 41 and the operation end 312 of the inner tube 31 together. The threaded shaft 41 further has a flange 412 between the first and the second retaining nuts 44, 45. The turning knob 42 is mounted around the threaded shaft 41 via a collar 47, which is provided between the first retaining nut 44 and the flange 412 of the threaded shaft 41 to enable rotation of the turning knob 42 with respect to the threaded shaft 41. The adjustment ring 43 is located between the operation end 312 of the inner tube 31 and the turning knob 42 and has, from top to bottom, a recess 432, a flange groove 434, and a threaded hole 436. The recess 432 has an end wall forming a pushing portion 438. The flange groove 434 is coaxial, and in communication, with the recess 432 and receives the flange 412 of the threaded shaft 41. The threaded hole 436 is coaxial, and in communication, with the flange groove 434 and is threadedly provided around the threaded shaft 41, allowing the adjustment ring 43 to move up and down along the axial direction of the threaded shaft 41 between a first position P1 and a second position P2. When the adjustment ring 43 is at the first position P1 as shown in FIG. 7, the pushing portion 438 of the adjustment ring 43 pushes the collar 47 of the turning knob 42 against the first retaining nut 44, thereby preventing the collar 47 from rotation. In this state, the turning knob 42 and the threaded shaft 41 form a single unit, meaning the threaded shaft 41 can rotate with the turning knob 42. When the adjustment ring 43 is at the second position P2 as shown in FIG. 9, the pushing portion 438 of the adjustment ring 43 does not apply any pushing force to the collar 47 of the turning knob 42, so the turning knob 42 can rotate freely without driving the threaded shaft 41 into rotation.

According to the above, the exposed length of the inner tube 31 (herein defined as the length of the portion of the inner tube 31 that is exposed from the outer tube 24) can be adjusted in the following manner to accommodate films of different widths. To begin with, the adjustment ring 43 is rotated to the first position P1 as shown in FIG. 7 to render the turning knob 42 and the threaded shaft 41 into a single unit. Then, the turning knob 42 is turned so as to rotate the inner tube 31 via the threaded shaft 41, moving the conical portion 324 of the positioning column 32 away from the wall of the conical groove 37 of the positioning sleeve 33, and only then can the turning knob 42 be pulled to adjust the exposed length of the inner tube 31. When the operation end 312 of the inner tube 31 is adjusted to a position adjacent to the top end of the roll of film 12, the turning knob 42 is turned in the opposite direction as shown in FIG. 8 in order for the conical portion 324 of the positioning column 32 to push the wall of the conical groove 37 of the positioning sleeve 33, thereby pressing the positioning sleeve 33 tightly against the outer tube 24 to secure the inner tube 31 in position. After that, a pressing plate 48 is mounted around the threaded shaft 41 and pressed against the top end of the roll of film 12, and the adjustment ring 43 is rotated to the second position P2 as shown in FIG. 9. The adjustment ring 43 in this state does not apply any pushing force to the collar 47 of the turning knob 42, so the turning knob 42 can no longer rotate the inner tube 31 via the threaded shaft 41. This prevents the inner tube 31 from getting loose due to inadvertent operation of the turning knob 42. Moreover, as the adjustment ring 43 is pressed against the pressing plate 48, which in turn is pressed against the top end of the roll of film 12, the roll of film 12 is firmly secured between the supporting base 22 and the pressing plate 48, and adjustment of the exposed length of the inner tube 31 is thus completed. An operator can now resume the packaging operation by holding the handle 26 with both hands.

In a nutshell, the film applicator 10 of the present invention allows the exposed length of the inner tube 31 to be adjusted according to the width of the film to be used, and it is the adjustment ring 43 that produces the positioning and releasing effects during adjustment. The present invention, therefore, enables a reduction in packaging cost by eliminating the need to prepare a plurality of inner tubes 31. In addition, the roll of film 12 in use can be easily replaced by dismounting the inner tube 31, removing the roll of film 12, mounting a new/different roll of film 12 around the outer tube 24, reconnecting the inner tube 31 to the outer tube 24, and then adjusting the exposed length of the inner tube 31. Since the outer tube 24 need not be dismounted, the replacing operation can be completed with ease. 

What is claimed is:
 1. A length-adjustable film applicator, comprising: a stand having a supporting base and an outer tube, wherein the outer tube has an end provided at the supporting base; an inner tube assembly having an inner tube, a positioning column, and a positioning sleeve, wherein the inner tube is rotatably and axially displaceably provided in the outer tube of the stand and has an operation end outside the outer tube and a positioning end in the outer tube, the positioning column is provided at the positioning end of the inner tube, and the positioning sleeve is threadedly connected to the positioning column such that, by rotating the inner tube, the positioning column is driven to either press the positioning sleeve tightly against the outer tube of the stand or loosen the positioning sleeve from the outer tube of the stand; and an adjustment assembly having a threaded shaft, a retaining nut, a turning knob, and an adjustment ring, wherein the threaded shaft has an end fixed at the operation end of the inner tube, an opposite end threadedly connected with the retaining nut, and a flange; the turning knob has a collar between the retaining nut and the flange of the threaded shaft and is rotatably mounted around the threaded shaft via the collar; and the adjustment ring is threadedly provided around the threaded shaft and between the operation end of the inner tube and the turning knob and is displaceable between a first position, at which the adjustment ring pushes the collar of the turning knob against the retaining nut in order for the turning knob to rotate the inner tube with respect to the outer tube via the threaded shaft, and a second position, at which the adjustment ring is away from the collar of the turning knob and allows the turning knob to rotate freely without driving the inner tube into rotation.
 2. The length-adjustable film applicator of claim 1, wherein the adjustment ring has a recess, a flange groove, and a threaded hole; the recess has an end wall for pushing the collar of the turning knob when the adjustment ring is at the first position; the flange groove is coaxial, and in communication, with the recess and receives the flange of the threaded shaft; and the threaded hole is coaxial, and in communication, with the flange groove and is threadedly provided around the threaded shaft.
 3. The length-adjustable film applicator of claim 1, wherein the adjustment assembly further has a pressing plate detachably mounted around the threaded shaft in order to be pressed against a roll of film mounted around the inner tube and the outer tube.
 4. The length-adjustable film applicator of claim 1, wherein the positioning column has a conical portion and a threaded connection portion extending from the conical portion, the positioning sleeve has two opposing sleeve halves and a nut between the sleeve halves, each said sleeve half has a pressed portion, each said pressed portion has an outer periphery abutting against an inner periphery of the outer tube and also has an inner periphery, the inner peripheries of the two pressed portions form a wall of a conical groove, the wall of the conical groove abuts against the conical portion of the positioning column, and the nut is threadedly connected to the threaded connection portion of the positioning column. 